Method of producing biodiesel from microalgae using thermo-responsive switchable solvent

Patent metadata

Field	Value
Publication number	US-11060120-B1
Application number	US-202017105465-A
Country	US
Kind code	B1
Filing date	Nov 25, 2020
Priority date	Nov 25, 2020
Publication date	Jul 13, 2021
Grant date	Jul 13, 2021

Abstract

The method for producing biodiesel from microalgae using a thermo-responsive switchable solvent includes mixing a thermo-responsive switchable solvent (TSS) in a hydrophilic state with microalgae at room temperature (25° C.); maintaining the TSS-microalgae mixture in the hydrophilic state for a cell disruption time period; raising the temperature of the TSS-microalgae mixture to switch the TSS solvent to a hydrophobic state; maintaining the TSS solvent in the hydrophobic state in the presence of immobilized lipase catalyst and methanol for an extraction/reaction time period to obtain fatty acid methyl esters (FAMEs) as the oils are extracted; lowering the temperature of the TSS-microalgae mixture to switch the TSS solvent back to the hydrophilic state; and maintaining the TSS solvent in the hydrophilic state for a product separation time period. The method may further include extracting the FAMEs from the TSS-microalgae mixture with a nonpolar organic solvent to obtain the biodiesel product.

First claim

We claim:

1. A method for producing biodiesel from microalgae using a thermo-responsive switchable solvent, comprising the steps of:
mixing a thermo-responsive switchable solvent (TSS) in a hydrophilic state with microalgae at room temperature of 25° C.;
maintaining the TSS-microalgae mixture in the hydrophilic state for a cell disruption time period to render oils in the microalgae accessible for extraction, the oils being triacylglycerides formed from three fatty acids connected to glycerol by ester linkages;
raising the temperature of the TSS-microalgae mixture to switch the TSS solvent to a hydrophobic state;
maintaining the TSS solvent in the hydrophobic state in the presence of immobilized lipase catalyst and methanol for an extraction/reaction time period for simultaneously extracting the oils from the microalgae and reacting the oils with the methanol in a transesterification reaction to obtain fatty acid methyl esters (FAMEs) as the oils are extracted;
lowering the temperature of the TSS-microalgae mixture to switch the TSS solvent back to the hydrophilic state; and
maintaining the TSS solvent in the hydrophilic state for a product separation time period to separate the FAMEs from the TSS solvent for use as biodiesel.

2. The method for producing biodiesel according to claim 1 , further comprising the step of extracting the FAMEs from the TSS-microalgae mixture with a nonpolar organic solvent to obtain the biodiesel product.

3. The method for producing biodiesel according to claim 1 , further comprising the step of extracting the FAMEs from the TSS-microalgae mixture with n-hexane extraction solvent to obtain the biodiesel product.

4. The method for producing biodiesel according to claim 1 , wherein the TSS is a mixture of propylene glycol, water, and a protic ionic liquid selected from the group consisting of N,N-dimethyl-N-ethylammonium acetate [N 1120 ] [C 1 CO 2 ]; N,N-diethyl-N-methylammonium methane sulfonate [N 1220 ] [C 1 SO 3 ]; N,N-dimethyl-N—(N′,N′dimethylaminoethyl)ammonium acetate, [N 11[2(N110)]0 ] [C 1 CO 2 ]; N,N-dimethyl-N—(N′,N′dimethylaminoethyl) ammonium chloride, [N 11[2(N110)]0 ]Cl; N,N-dimethyl-N-ethylammonium phenylacetate, [N 1120 ] [C 7 H 7 CO 2 ]; and N,N-dimethyl-N—(N′,N′dimethylaminoethyl) ammonium octanoate, [NN 11[2(N110)]0 ] [C 7 CO 2 ].

5. The method for producing biodiesel according to claim 1 , wherein the TSS is a mixture of propylene glycol, water, and N,N-diethyl-N-methylammonium methane sulfonate [N 1220 ] [C 1 SO 3 ].

6. The method for producing biodiesel according to claim 1 , wherein the TSS is a mixture of 6 wt. % N,N-diethyl-N-methylammonium methane sulfonate [N 1220 ] [C 1 SO 3 ], 30 wt. % PPG, and 64 wt. % distilled water.

7. The method for producing biodiesel according to claim 6 , wherein the cell disruption time period is between 0.5 hours and 3 hours.

8. The method for producing biodiesel according to claim 6 , wherein the cell disruption time period is 0.5 hours.

9. The method for producing biodiesel according to claim 6 , wherein said step of raising the temperature of the TSS-microalgae mixture to switch the TSS solvent to a hydrophobic state comprises raising the temperature of the TSS-microalgae mixture to 45° C. to switch the TSS solvent to a hydrophobic state.

10. The method for producing biodiesel according to claim 6 , wherein the extraction-reaction time period is between 0.5 hours and 3 hours.

11. The method for producing biodiesel according to claim 6 , wherein the extraction-reaction time period is 3 hours.

12. The method for producing biodiesel according to claim 6 , wherein said step of maintaining the TSS solvent in the hydrophobic state in the presence of immobilized lipase catalyst and methanol for an extraction/reaction time period comprises maintaining the TSS solvent in the hydrophobic state in the presence of immobilized lipase catalyst and between 0.02-0.2 ml methanol per gram of microalgae for an extraction/reaction time period.

13. The method for producing biodiesel according to claim 6 , wherein said step of maintaining the TSS solvent in the hydrophobic state in the presence of immobilized lipase catalyst and methanol for an extraction/reaction time period comprises maintaining the TSS solvent in the hydrophobic state in the presence of immobilized lipase catalyst and 0.15 ml methanol per gram of microalgae for an extraction/reaction time period.

14. The method for producing biodiesel according to claim 1 , wherein said step of mixing a thermo-responsive switchable solvent (TSS) in a hydrophilic state with microalgae at room temperature of 25° C. comprises mixing a thermo-responsive switchable solvent (TSS) in a hydrophilic state with microalgae at room temperature of 25° C. while the microalgae is still in a wet state after harvesting.

15. The method for producing biodiesel according to claim 1 , wherein said step of mixing a thermo-responsive switchable solvent (TSS) in a hydrophilic state with microalgae at room temperature of 25° C. comprises mixing a thermo-responsive switchable solvent (TSS) in a hydrophilic state with microalgae at room temperature of 25° C. after the microalgae has been dried.

16. The method for producing biodiesel according to claim 1 , wherein said microalgae comprises Chlorella sp.

Assignees

• Univ United Arab Emirates

Inventors

• Al-Zuhair Sulaiman Abdulrazak
• Ismail Mukhtar Ahmed

Classifications

• Y02E50/10

  Biofuels, e.g. bio-diesel · CPC title

• C12Y301/01003

  Triacylglycerol lipase (3.1.1.3) · CPC title

• C12P7/6463

  obtained from glyceride producing microorganisms, e.g. single cell oil · CPC title

• C12R2001/89

  Algae {; Processes using algae} · CPC title

• C12N1/12

  Unicellular algae; Culture media therefor (as new plants A01H13/00) · CPC title